Furniture is an important appliance for daily life, and is usually composed of a table surface on four posts. With the increasingly rapid pace of life and the limitation of living space, the traditional furniture is inconvenient for use and occupies too much space.
In recent years, foldable furniture has become increasingly popular. The foldable furniture (or foldable frame) is a furniture which can be folded while in transportation or when not in use. For example, foldable furniture can be applied in modular kitchen designs, service carts, work benches, craft tables, gardening carts, and storage shelves.
Though the foldable frame can be folded to a certain size, the traditional foldable frame is still relatively large and heavy after being folded.
Furthermore, in order to reduce the cost of transportation, manufacturers will ship furniture in knock-down form ready to be assembled (RTA). As a result, customers will have to assemble the furniture after receiving the components, which leads to much inconvenience.
Accordingly, it is highly desirable to have a foldable frame which is preassembled, compact for transportation and storage, and can be unfolded to become a table or cart in their maximum size configuration. Furthermore, it is also desirable to be able to transform the folding frame from folded to open form very easily.
In U.S. Pat. No. 6,123,207, Mast discloses a shipping rack easily convertible to an extended mode for storing and shipping product, a display mode for displaying product, and a collapsed mode for storing the rack itself. The rack includes a pair of central support columns and a pair of outer posts on either side of the columns. A plurality of shelves is pivotally mounted between the posts and columns. In the extended mode, the shelves are horizontal. As the columns are raised with respect to the posts, the shelves pivot to the desired inclination. Once the shelves are essentially vertical and the posts are draw close to central columns, the rack is in the collapsed mode. The rack can be secured in any mode by a strut. A spring counterbalance system installed within one of the central columns assists the mode converse on of the rack.
This rack uses two central supporting posts and four side supporting posts to form the supporting structure, and is folded and unfolded through the spring counterbalance system. This structure is complicated.
In U.S. Pat. No. 5,131,547, Goldberg discloses a collapsible storage rack assembly including a plurality of upstanding, generally inverted U-shaped frame members between which extend a plurality of vertically spaced, collapsible shelf assemblies. Using crossbeams for frame support and foldable movement, the storage rack can be easily and quickly opened for use by moving the frame the frame members away from each other. In a similar manner, the storage rack can be easily collapse position, with the shelf assemblies collapsing by upward hinging movement. In the close and collapsed position, the shelf assemblies are substantially completely nested within the frame members, thereby facilitating convenient handling, shipment, and storage of the construction.
In U.S. Pat. No. 5,131,547, intersecting cross-braces are used to realize the folding of the frame. However, owing to intersecting cross-braces, the structure of the frame is also complicated.